Mike- guess it's a bit of a cop-out but I don't think the Soviets were very picky about colours as long as it was in the ballpark and the harsh weather would fade and discolour anything so I wouldn't get too much of a hangup on getting it perfect. 

The two grays specified were AMT -11 blue gray and AMT-12 dark gray. Akan makes these specific colors. You can at least Google them and try and match them.  

+1 to what NathanT said. I read a review of Akan paints in a recent issue of FSM, and according to that, they're accurate, though I haven't used them myself.

Model Master may have something as well. I have some Soviet colors in Model Master, but can't recall at the moment if they've got the two-gray scheme.

-BD-

Model Master never did those grays. Aeromaster and Polly Scale did, but those lines are OOP. A rough approximation for substitutes from the MM line would be Dark Ghost Gray 36320 and Gunship Gray 36118. Not exact, but they will look the part. 

Stik is right. I've gotten real close mixing Gunze dark sea gray with some blu-gray mixed in for AMT 11, and extra dark sea gray mixed with black for AMT 12. 

Yeah, you could easily mix something up. But I'm not sure what to recommend. I have the Polly Scale versions in my stash. 

You may want to look at IPMS Stockholm or Cybermodeler sites. Both have nationality paint chart pages.

Appreciate it Stik. My friend at work told me about the Stockholm website as well; said it's very informative. I figure I can mix up a few batches to try out on cardstock to get the closest approximation. I ordered MM Earth Grey but it seems far too brownish for what I want. I also found a grey enamel in my Humbrol stash that may be doable as well. Thanks again buddy!

There is also a good website on  WWII Soviet aircraft modeling, but I don't recall the site name off the top of my head. Google VVS modeling, or modeling the VVS, and check the results.